Dry cell and method of producing same



` Oct."`12","\1937.`` y o. E. RUHFF ETAL` D 2,095,421

" DRY CELL AND METHOD OF PRODUCING SAME Filed Jan. 23, 195e uw :i

y WMM W @3,

` Wis., "assignoi's to Marathon Battery Company, Y, Wausau,*Wis., a corporation `of Wisconsin` M relates cells and their method oiimanufaicture. andis ap-` the' manufacture off which ,the .core is fabricated as" a s`e1gtiaige` ,unit `and, thenlput` into` operative association `with, theainc canbylmeanswof ag'elatinous electrolyte surrounding` the` core "and occil'- can.`

` `ganese dioxide; ,carbonaceousfflmaterial,y faim-` moniuin ichloride, Wzinc" chloride, and ,"water, and i i such cores are ,usually formedu by preparing the sqthattne latter isintrauy cisppsei ijn thercdre. ,e The lmoldableriicharacter of `the material" en-` ablee theforr'riation of good coreslby'coinpression y butirrespectiye of ,how Well formed theyniaybe,

" wheninserted intoiafzinc can, whichhas a rela` -face's` which are Asuiiieiently hard and durable to tivelyisharp upper edge,` pertions4 thereof are withstand the handling,tdwhich'such'cores' are 25 likelytospfall, orbe scraped` orlbrolen ofif ,Also subjected during the manufacturing operations; i thereuis the-further dangerxof partialdi'sintegra- Suchfcores Aare known `(as unwrapped cores. i tionfof lthecore or `a washing loiof anylloosely 1 4"One procedurefformaking batteries having unadhering crumbsorl particleszwhentheLcore is wrappedlcoresfis described and claimed Yinthe brpughtxintq contact with the ungelatinized elecapplicants"4 copending` application `Serial `Np. 30

i trolyteriiixture 1during` the period'before theleleo- '156,586,fled December 8,1934. In accordance trolytewcan,bejconvertedltdarelatively stiffgelatf witlfi` said invention, a hardened casing for the i Il finous consistency i i 1 f i, i i f coreis` supplied'bythe deposition throughout a i The maintenance ofthe physical `forrn of the smallv region of the surfaceofthe core of an core andthe `preveriftion of its disintegrationy after l amount of crystallizable substance', such as sal 35 i ithas beenplacediin'the zincfcupare essential to ammoniacwhichis already'present in the core,

the (productionllof,satisfactory commercial cells,` `as' a constituent lofthe depolarizing` mixture. as thescalirig olffigof-particles"ofMdepolarizingrnaf Such deposition may be' effected in the manner x terial andthecollection thereof adjacentthebot#` outlined `in` said `copending application with the 1tomofmthecell-ibetweenthe oorefandthe'zinc resultlthata:hardened casing isformed on the 40 i Lcup. Willoause shorticircuits in thefoellforestablishlocalqaction thereirneither,or` both of which asacoinmercial productionsc materially shorten ,i g demanded fordryicellsrin use.

, i Infprior commercial ,pnactice` tornaryto maintainfthe physical. 'form of the core by means of a wrappinglof cheese cloth or some similar material. i Suchcloth or material has i 'been found `to be wellisuited for thepurpose as it retains `the core partieleswhilehatthe 'same time it:` readily `passes "the,leleci'lrolyte` `rn'iidiure so.1 that Aplicable t'olthat tiypelof` dry cells whichfhave a central icore[comprisingV a ycarbon. pencil andla l oompreesedimassof depolarizing material, and in 0, `pyingithespacebetween thecore and/,the zinc? mixture as a damp, fairly cohering mass and then irlerittin the'battery.`

i compessingthejsarne laround, thefcarbon pencil such cores, nevertheless, are relatively'iragil'e and will ,entirely destroyane usefulness of. the ceu its 1ife,1thatit willlffkallfblowth'e standardsvfnow [the latter `intimatelycointactsv `the core kwithout Aausingl `objectionable air` llms, togbel `-formed therebetween. However," oheesecloth` and such other materials are" relatively expensive'and their use adds materially' to the cost of, the cell particularlyasthe wrapping `operationsvareboth time consuming and costly.

i .i In addition to the aboky'e, it hasffa-lso, beenloustomaryfincoxnmercial pacticefto provide-ari insulating `washer i`n the bottomof the zinc can so as to prevent contact betwenthe core, or particles thereofand the bottoml of` the can.` Such Wash# e ers are usuallyformed as disks'of waited paper, or i inwsome cases,4 specially `formed `washers designed to have'alcentering function finl the zine can.

" "Such disksuand `spacing Awashers i addmaterially tothe costjof `dry cells and in addition, require additionaliassembly steps',` for their proper `place i In `order `t reduce the 'cost of i, batteriesoithis typel andt o simplify the `construcztion and mini mize theunanufacturing steps'ifvarious f attempts haver been `made to` eliminate the cheesecloth or I other. wrappings'` formerly :requiredV for the `core i anddtorv provide cores with coated or hardened surcore'yvhich renders it unnecessaifyto use cheesei l cloth or' other'wrappings'for the core. e

Ilfhe presentinventionis an improvement upon the invention describedand claimed inthe applicants copending applicationabovev referred to and relateslto the provision of; means,' adapted for use ihconjunction with the improvements of said i presence of which greatly assist in the ready assembly of the core in the can during the manufacture of the dry cells.

These and other objects not specifically enumerated are contemplated for this invention as will readily appear to one skilled in the art as the following description proceeds. This description can be more readily understood when considered in the light of the accompanying drawing, in which,

Figure 1 is a perspective view of a core made in accordance with the present invention, and which is partially broken away to better disclosev the construction thereof, and

Figure 2 is an elevational view in cross section of a completed cell constructed in accordance with the present invention.

By referring to the drawing, it will be noted that the invention is illustrated as embodying a compressed core I0, formed in the customary way in cylindrical form of the usual depolarizing mixture and including an imbedded carbon pencil II. As disclosed in Figure l, by the portion broken away, the region I2 adjacent the surface of the core is hardened by means of a recrystallization of a substance contained in the depolarizing mixture, such as sal ammoniac so that the surface region of the core is relatively hard and resistant in the manner described and claimed in applicants copending application above referred to.

This hard and resistant outer surface region renders the core capable of use Without being wrapped and Withouasuifering the likelihood of damage heretofore common in the manufacture of cells of this type. As pointed out in said copending application, the cores may be formed in various ways but by way of example, after being tamped and cleaned, may next be heated by passing the same through a heated oven or other suitable means for drying out the surface region thereof. The drying or baking is satisfactorily accomplished when conducted in a five foot electrically-heated oven through which the cores are passed in an upright position on a conveyor formed of heavily enameled Wire screen pieces which may be attached by special links occurring at intervals of approximately one foot.` Y

With this construction the heat may be supplied by hot air from below the screen sections of the conveyor so that the hot airwill rise and in so doing, will come in intimate contact Withthe cores. The speed of the conveyor may be adjusted at a desired rate to cause the cores to remain in the oven for approximately five minutes and th`e heat of the oven may be adjusted for this heating period to approximately 350 degrees F.

The above practice provides for the outer hard-` ened surface as above described in said copending application and said practice shall be modified as hereinafter indicated in the following invention.

A mixture of a strong solution of sal ammoniac at or near its boiling point and a quantity of wood fiour is prepared. This is preferably provided in such form that the wood flour is maintained in suspension in the hot sal ammoniac solution. As a preferred formula the following quantities may The wood flour may be of any suitable degree of neness, although good results are obtained when wood flour subdivided to mesh is employed. It is to be understood however, that applicants do not wish to be limited to wood flour of any particular mesh as obviously other degrees of subdivision will also serve well.

In accordance with this invention, after the cores are tamped and cleaned in accordance with the practice of applicants invention described in their copending application, and before they are dried or heat treated, they are dipped in the above described mixture so as to apply a substantial quantity of said mixture adjacent the bottom portion thereof in a manner illustrated at I3, in the accompanying drawing. This invention is not to be limited however, to the application of this material by dipping as it may be applied by spraying or any other suitable method.

Furthermore, the applicants do not wish to be limited in regard to the extensiveness of the applied material throughout the height of the core as obviously variations in this regard may be practiced according to the results desired.

The cores so treated are'next subjected to a drying operation already described in connection with the practice of the applicants invention of said copending application. In this case however, the cores are preferably inverted sol as to prevent the moist coating material from running down and collecting inbeads or globules atv any pointon the core. It has been found when subjected to a drying operation as hereinabove described, namely, for approximately five minutes, at substantially 350 degrees F. that not only is a hardened casing formed on the body of the core, but that the insulating and centering ring on the bottom thereof becomes sufficiently hard and dryto enable the core to be placed directly within the cans without further precaution or care.

' It Will be noted that it is preferable to have the coating mixture of such a consistency as to enable the production on the core of a rather substantial ring of coating material somewhat in themanner illustrated at I3 in the accompanying drawing. This ring, in addition to its insulatingfunction, thus serves as a centering means by which the cores are maintained in a more or less central position within the can I4 with the avoidance of all liability of the sides of the core touching the inside surface of the can. Accordingly, this feature eliminates the necessity for special centering means of the type usually employed with unwrapped cores. As a result the assembling operation can be quickly and effectively accomplished without the expense of additional centering means and without the delay and expense lof bothering with any special devices for centering the core. In operation, it is only necessary to drop an ordinary insulating disk Washer II in the bottom of the can and then place the core within the can. With the insulating ring at the bottom of the core', proper centering of the core automatically results. The washer I1 can be of slightly less diameter than the can so as to readily assume a fiat position on the bottom of the can. In actual practice the mixture which is saturated with sal ammoniac is kept mildly `agitated at about its boiling point. Then the vcores are preferably dipped to a depth of between one-sixteenth to one-eighth of an inch for the ordinary small size cores.

As above described, the drying or baking treatment is carried out the same as described in applicants copending application except that the cores are inverted so as to prevent the gathering of the coating material in drops or small lumps at any point on the core. The cores, as withpolarizing ri ablfbyfthefa www be easilyA kept in `suspe batteries? ammoniac-and wond flour ardfthereaftercausing "depolarizing mixture, rendering `said mixture 1 Solution Ofsai al'flfcmcnd Wood urand y rnoldabl" by thadditionof Water,v forming said thereafter Sub-Willing Sald Gorfand Sad Protec' `tive `ring ofj a" strong solution` ,pf` said electro. saidsal ammoniac contained insaid `core and thereafter causing eyaporation of the water` in y cien'` Gvipifcvde e `relatively hard eind ,tough dfsaid` coreand said potetive 'ring to angextent cesingscr Seid core and protective ring consist- Which causes depsitiori of said electro-chemicaling fsaliammniaci y "-1y` active substancecontained.irif` said core` and` 6. ThCmetlflQd 0f DIOdJucingcOlcS foi dry cells F Isaidprotcszctiye ring inamountsuilioient t0 providv4 Mhich comprises DIOVding a depolallizngmixtule70 `a 4relatively `hard andftougl'xA Casing `for said core' 1 having'a quantity cf Sal ammoniac therein, ren` and saidprotective` ring consisting vof said elecdering SaidmigturomOIdabIe by the addition of `tro-chemically activesubstanc. 'f Water', forming said coreLapplying to the` bottom `2. The method" of producing oo res for dry cells of saidooreaprotetive ring `of a strong solution which cmprisesprvi'ding adepolarzing mixture f" oils'al ammoniac and wood our,` "andther'eafter 75 fandtougheningeirectupon thepjarticles of vsaid tomi 0f Seidcore e Protective rime 01E e strong 60 vcore, appiyijngto the lmtomofsamcorewrote@T tiveririg tea dryingaction whereby e bortioprof f1 s.

" hemiauy activesubsranceiand wood noupana seidprefectYe-rins is deposited in amount sur- 65 tively hardand tough casing for said core and said protective ring consisting of said sal am rsubjecting saidA core and protective ring to a'- heating action for drying saidvcore and protective ringl to deposita portionof said sal ammoniac'from solution throughout the outer'` regions of said core and said protective ring so that said sal ammoniacas deposited provides a. relajmoniac.

'7. The method of producing ,coresfor drycellsl which comprises providinga" depolarizing mix- Y ture having a quantity of sal ammoniac therein,

rendering said mixture moldable bythe addition 1 of water, forming said core, applying at the bottom of vsaid core a protective ring formed from a mixture of a strong solution 'of sal ammoniac at or near its 'boiling point and a quantity of Wood our', thereafter cooling and drying said mixture so as to deposit from solution ya portion of said sal ammoniac toy forman the surface of said protective ring av hard and tough casi'ngconsisting of sal ammoniac. y t

8. The method of producingcores for dry cells which consists of forininga'core of depolarizing mixture, applying to the `bottom thereofa protec- C tive ring comprising a. mixture of wood our'and a -strongsolution of a. substance which acts electro-'chemically Vas an `ingredient of the mixture o! said core andwhich is water-soluble and capable' of being deposited from solution to exert a hardening andtoughening effect,'thereafter causing evaporation of thewater in said protective ring to an extentwhich causes deposition of said electro-chemically acted substance vin said protective ring in amount sumcient to provide a rela-v tively hard and tough casing for said protectivel ring consisting ofsaid electro-chemi'callyl acted substance. r o

9. The method of producing cores for dry cells which comprises forming a core of a. depolarizing mixture, applying to the bottom of said core a" protective ring comprising a mixture of wood our and astrong solution of sal ammoniac, thereafterxcausing evaporation of the water in said protective ring to an extent which causes deposition of said sal 'ammoniac containedinsaid 12. A core for dry cells of the type herein described adaptedto be used without a wrapperl thereon made in accordance with the process defined in claim 9. s s

`15. A dry cell of the typeherein described com. prisinga zinc can and a'sgelatinized electrolyte,

and an unwrapped core madein accordance with the process defined inclaim 1.4

16. A dry cell of the type herein described comprising a zinc can and agelatinizedy electrolyte, and anllpwrapped core made in accordance with the vprocess defined jin claim 4. i

1'7. Adry cell of the type herein described' comprisng a zinc can anda'g'elatinized electrolyte, and an unwrapped @remade` in accordance with the process defined in claim '1.

18'. A drycell of the type herein described comprising a zinc can and a gelatinized electrolyte,

and an unwrapped core lmade in accordance with the process defined iniclaim 8.

19. Afdry cellof the' type herein described comprising a zinc can and a. gelatinized electrolyte, and an unwrapped core made in accordance with the process defined` in claim 9.

20. The process o1' producing dry cells which consists in forming a core bymolding a mass of a depolarizingmixture which includes in its composition a quantity'of sal ammoniac,"applying to the bottom of said core a. protective ring of a strong solution `ofsal ammoniac and wood flour, causing a portion of the sal ammoniac to be taken into solution. and thereafter causing 4a portion thereof Athroughout the region of the surface of said core and said protective ring to bev deposited by the evaporation of moisture in amount sufficient to provide a relatively hard and tough casng'for said'core and protective ring, consisting of said `sal ammoniac, thereafter placing a liquid gelatnizable electrolyte in azinc can, placing said core andl protective `ring in an upwrapped condition centrally in said can and maintaining the core so positioned while gelatinizing the electrolyte under the influence'of heat and finally sealing the top of the can to form A.a completed cell.

OTTO E. R'UHOFF. EDGAR. J. MCEACHRON. O'I'IO J. KRUEGER. GEORGE H. SCHROEDER.

tent HO 42,095, 421

\ CERTIFICATE 0F CQRREGTION. Y 5

` v i Butcher l2, 195'?.

OTTO E; RUTHOFF,` ET AL. Y

i Itis herebyv certified `that err-cr" cppers in the."pifimnad specification i f ofthek abgve humbered patent requiringcrrectonasfollows: Page liv, `Second column, `13.115551 19 and 148, claims "176120 `I'eispe:etzLinfeZLy, for "uywrpped'i z'esldv unwrappid,-` and that thc` said Letters'fatent shmird` b`e read with these corrections `therejmi that tkleisaine` may onfrm to bhl record of the case in the Patent officc.;r

`B63111129' Van Arscale,

{Seal} V i f Acting Commissioner of Patents 

